Cillian Murphy has explained that the now fashionable undercut he has on the hit BBC show was intended to stop lice spreading when it was first trendy 100 years ago.

Cillian Murphy doesn’t get why people are so enamoured with his Peaky Blinders haircut.

The Irish actor was an in-demand movie star before succumbing to the lure of television work.

He’s been playing Birmingham badboy Thomas Shelby in hit BBC drama Peaky Blinders since 2013, and is currently filming the highly anticipated fourth season of the acclaimed series. And for the past four years, Cillian has become synonymous with gangster Thomas’ undercut hair style, with the cut spawning plenty of copycat looks.

“But people like the undercut thing; people go to the barber and ask for a ‘peaky cut’,” Cillian began to British magazine ShortList. “It’s crazy that people like it, it’s not grown on me in four years now. I normally keep my hair long.”

Peaky Blinders is based on a real life gang, who operated in the West Midlands, England, in the aftermath of World War I.

The hairstyle worn by Cillian and his co-stars, including Paul Anderson and Joe Cole, is realistic of the time, though the 41-year-old has now revealed the real reason men in the ‘20s wore their hair like that.

“But they do realise the people in turtlenecks in Hackney (London) with this haircut, do they realise it was styled this way to prevent lice? Tell ‘em they have got the lice cut, see what they say then,” he smiled.

Cillian can next be seen in Christopher Nolan’s Second World War epic Dunkirk, where he plays a shell shocked soldier, alongside an all-star cast that includes his Peaky Blinders co-star Tom Hardy, Oscar winner Mark Rylance and One Direction star Harry Styles in his acting debut.